By means of a frog bio-assay cardiotoxic material produced in blood during storage has been identified as being a heat stable compound with a molecular weight between 500-3,500. It is proposed to determine the hemodynamic response in the dog to an infusion of the material into the coronary arteries. In view of the similarity by bio-assay of the humoral shock factor, though the molecular weight is larger than 10,000, a similar set of experiments will be done using material prepared from blood drawn from animals after a substantial period of hemorrhagic shock. An attempt will be made to further identify the chemical nature of the material in stored blood. Using isolated rabbit lung preparation it is proposed to investigate whether there is a pulmonary toxic factor produced in blood during storage. It is proposed to examine the transfer of these factors, cardiotoxic and pulmonary (if present) to the transfusion recipient. BIBLIOGRAPHIC REFERENCE: Nagler, A., and McConn, R. Humoral factors in shock. In: Shock: Clinical and Experimental Aspects. Ed. I. McA. Ledingham, Vol. 4. Monographs in Anesthesia. Pub. Excerpta Medica 1976.